Spark plug



Aug- 12 1924.

L. SCHMEDT SPARK PLUG Filed Sept. 14 1921 INVENTOR ZamkrZ aiz miaf BY C F 6 ATTORNE Patented Aug. 12, 1924.

UNITED STATES LAMBERT SCHMIDT, O'F BROOKLYN, NEW YORK.

SPARK PLUG.

Application filed September '14, 1921. Serial No. 500,604.

To all whom it may concern:

Be it known that I, LAMBERT Sonatina", a

citizen of the United States, and resident of i the borough of Brooklyn, county of Kings, city and State of New York, have invented certain new and useful Improvements in Spark Plugs, of which the following is a specification.

The present invention relates to improvements in spark plugs in which the sparking points or terminals are kept clear of deposits of carbon by the circulation thereabout of currents of air, this action being accomplished automatically by the suction of the engine.

It is an object of the invention to pro vide an improved spark plug in which the terminals, and particularly the central rod electrode, will be kept in a relatively cool state by being enveloped by a constantly changing atmosphere of cool air caused to circulate thereabout in spiral streams and which avoids the deposits of oil and carbon upon the electrodes which would otherwise occur where the latter are allowed to become highly heated as in the case of standard spark plugs in use generally at the present time.

Another object of the invention lies in providing an improved spark plug of a simple and inexpensive character, in which air from the atmosphere is adapted to be drawn in and circulated about the central electrode on the uction-of the piston, while an improved valve is used to prevent the escape of the compression when the piston is traveling upwardly as a preliminary to the explosion of the gases.

Some attempts have been heretofore made to provide an air cooled spark plug,. but in prior constructions it has been found that repeated, rapid and. forceful reciprocation of thevalve acting in conjunction with a stationary and rigid seat, in a short time pits the valve and the seat and otherwise injures both the valve and its seat and prevents a proper closing of the valve, leading to an esca e of the compression and conseuent ine ciency in the engine. A further ifliculty with prior constructions is that the rapid operation of a ball valve wears a groove of substantially its own size in the valve seat where it is afterwards found to stick and resist movement under the'infiuence of the partial vacuum and atmospheric pressure. The device thus becomes inoperative.

It is a further object of the invention to eliminate this difficulty by providing a resilient abutment for the valve to yieldingly receive it when drawn from its seat by the atmospheric pressure.

A further object of the invention is to provide for a whirling or spiral path for the cooling air current within the insulator body whereby to keep the pocket between the insulator and rod electrode clear of carbon at a point where the latter accumulates undesirably and causes short circuiting.

A further object of the invention is to provide a spark plug in which the intensity of the spark will remain constantly unchanged and unaffected by long use of the motor and without being impaired by the deposit of carbon to the end that the motor may operate efficiently on a small amount of gasoline and constantly in a satisfactory manner.

l/Vith the foregoing and other objects in view the invention will be more fully described hereinafter in conjunction with the accompanying drawings, wherein like reference symbols refer to like or corresponding parts throughout the several views and in which.-

Figure l is a vertical sectional view taken through a spark plug constructed according to, the present invention. I

Figure 2 is a top plan view of the priming cup.

Figure 3 is a horizontal sectional view taken on the line 3-3 in Figure 1.

Figure at is a similar view taken on the line H in Figure 1.

Figure 5 i likewise a transverse sectional view taken horizontally on the line 55 in Figure 1.

Referring more particularly to the drawings 1 indicates the cylinder head of an internal combustion engine and 2 the casing or metallic shell of a spark plug having ex ternal threads 3 by which the plug is secured removably in the head 1. The casing or shell 2 may be of a standard construction having a wrench engaging portion 4 and internal threads 5 at its upper end to receive a nut 6 by which the porcelain core 7 is detachably held within the casing or shell and with its external shoulder 8 resting firmly against the internal ledge 9 of the casing or shell 2. A gasket 10 is desirably placed between a portion of the nut 6 and the upper surface 11 of the shoulder 8. The axial bore 12 of the insulating core is made of a diameter slightly greater than that of the standard plug to receive a tube 13 hollow from end to end and projecting at its lower end down into the petticoat 14 which depends from the insulating core body 7. A flange extends outwardly from the tube 13 to engage a shoulder 16 made at the base of the bore 12. The central rod electrode .or sparking point 17 is secured in the lower end of thetube 13 and extends down beneath the lower end of the shell 2 and into the cylinder head where it bears a desirable relation to the companion sparking point or electrode 18 carried by and in the electrical connection with said shell or casing 2.

In the tube 13, beneath the flange 15 and well within the petticoat 14 are provided a number of tangential ports 19, opening through the outer side of the tube and placing the space about such tube and within the petticoat in connection with the interior of the tube. The ports 19 are preferably inclined to radii of the tube or in other words are disposed diagonally for the purpose of causing the air jets to impinge at a substantially acute angle and in a downward direction against the adjacent wall of the petticoat 14. This wall is circular in hori zontal cross section and is frusto-conic-al in elevation with its basal or wider portion disposed at the bottom.

The circular character of the wall, in combination with the particular inclination given the ports 19 will require that the air take the circular course indicated in Fig ure 3; while the conical disposition of the wall will induce a downward flow of these circular air currents such as will convert the stream into a substantially spiral flow. The upper end of the rod electrode 17 is pointed or coned as indicated at 20 for the purpose of encountering and dividing the descending air currents and diverting such currents outwardly and downwardly through ports 19..

The upper end of the tube 13 is screw threaded as represented at 21 to receive a nut 22 abutting against the upper end of the insulating core 7 whereby to hold the tube and the central electrode 17 in place. Above the nut 22 is a second companion nut 23 cooperating with the first nut in the capacity of a lock and further providing a protective cap for the upper end of the tube 13, in which cap is placed a screen 24: lying at the base of a depression 25 which constitutes a priming cup. Directly within the upper end of the-tube 13 is placed a ball check valve 26 adapted to close against a seat 27 above and to operate between the seat and a resilient abutment 28, which for instance may be in the form of a coil spring resting upon an internal shoulder 29 within the tube.

In the assembly of the device, the shell or casing 2, nut 6 and insulating core 7 are all of substantially standard construction, except that the bore of the insulating core is preferably slightly greater in diameter than the diameter now usually provided. These parts may be associated in the customary manner. The tube 13 is inserted upwardly through the bore 12 before the nuts 22 and 23 are put in place. The tube is thrust through the petticoat 14 until the flange 15 is arrested by engaging the shoulder 16. The nuts 22 and 23 will then be put in place by securing them to the upper projecting end of the tube. The device is now in readidicated in Figure 1. The lead or wire from the distributor may be placed between the nuts 22 and 23, or elsewhere. The shoulder or casing 2 of the plug is grounded on the cylinder 1 in the customary manner.

The operation is as follows:

The sparking takes place across the gap between the electros 17 and 18 and ignites.

the compressed gas within the cylinder head 1, consequently driving the piston down on its working stroke. When the piston subsequently ascends, the burned gases are expelled and the next downward stroke is for the purpose of drawing in a requisite fresh charge. On this suction stroke of the piston a partial vacuum will be created within the cylinder head 1, resulting in the falling of the check valve 26 from its seat, aided forcibly by atmospheric pressure, and by rush of air past the valve, downwardly through the tube and out of ports 19 in conformity to the showing of the arrows. The cool air from the atmosphere circulating about the electrode 17 will preserve the same in a much coolerstate than electrodes are kept at the present time. This is important as it reduces the aptitude of the electrode for accumulating carbon deposits, and it prevents the carbon from incorporating itself intimately with the metallic electrode, which is a source of inconvenience with the present type of plugs. The air has a tendency, circulating as it does, in'a spiral path downwardly about the central electrode to brush off carbon and oil mechanically. Furthermore, the porcelain is kept cool by the constantly changing atmosphere and is consequently not so apt to crack or to disintegrate. The ball check valve 26 when pulled away from its seat 24: is always subjected to vice out of operation. On' the contrary the resilient abutment 28 yieldingl receives the ball withoutinjury thereto an without any injury to adjacent parts of the device. In

co d weather the priming cup 25 may be filled with a sup ly of liquid gasoline, which is drawn throu the screen and valve upon the suction stro e of the motor and does not inasmuch as the entire charge is completely burned and the formation of carbon is prevented to any great extent on this account. Knocking and pre-ignition are avoided. The air about the sparking points also pro- -vides suitable quantities of oxygen to support the combustion and to convey the firing to all parts of the charge instantly so that its prompt .efiect will be felt. upon the iston and'ln the efiiciency of the motor.

aving thus vdescribed one satisfactory and practical embodiment of my invention, it is nevertheless understood that the same is susceptible to many other modifications, and I accordin 1y reserve the privilege of adopting all suc legitimate changes as may be airl embodied within the spirit and scope o the invention as claimed. I

'nally threaded end projecting ower of the motor is thus What is claimed is 1. A spark plug comprising a casing, an insulating core secured in said casing provided with an internal shoulder, an electrode mounted in the core and having a flan e to engage upon said shoulder, said electro e including a tubular portion having an exterbeyond the core, retaining means threade thereon, the other end of the core being provided with a petticoat having its inner surface spaced from the electrode, the wall of said tubular portion of the electrode having a series of tangentially disposed ports therein, means within the tubular electrode adjacent to said ports to direct air outwardly and downwardly therethrough against the wall of said petticoat in a series of spiralling streams and an air controlling valve mounted in the up er end of said electrode.

2. A spar plug comprising a casing, a tube adapted to be positioned axially therethrough and means for detachably retainin sand tube in operative position, said tube ad acent its lower end being provided with a series of diagonally inclined ports tangentially disposed with relation to the bore of said tube, and an electrode element fixed in the lower end of the tube bore and having a conical terminal portion located adjacent said series of ports to divert air through said ports and direct the same in a series of downwardly spiralling streams around said electrode;

In testimony that I claim the foregoing as my invention, I have signed my name hereunder.

LAMBERT SCHliflDT. 

